Further Python3 fixes.

gui/scyther-gui.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 """
 	Scyther : An automatic verifier for security protocols.
 	Copyright (C) 2007-2013 Cas Cremers
@@ -193,7 +193,7 @@ class ScytherApp(wx.App):
 
         # License option may abort here
         if opts.license:
-            print Scyther.GetLicense()
+            print(Scyther.GetLicense())
             sys.exit(0)
 
         # Load preferences file